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Everything You Need to Know about Toyota ECU

Common symptoms of a bad Engine Control Unit (ECU) on a Toyota. How to reset a Toyota ECU. Step-by-step procedure on how to replace the Engine Control Unit (ECU) on a Toyota.

ESTIMATED TIME 20 - 30 mins
DIY COST $ 1000 - 3000
DIFFICULTY Easy

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Symptoms

The most common symptoms of a failing Toyota ECU include:

  • Check engine light stays on
  • No communication via the OBD-II port
  • Can't turn on the ignition
  • Toyota will not start
  • Engine stalling or misfiring and can't be fixed
  • Randomly losing spark/power
  • Randomly losing injector pulse 
  • Intermittent fuel pressure loss
  • Fuel pump failure
  • Intermittent starting problem
  • Transmission issues such as hard shifting
  • Immobilizer/Security light stays on
  • Trigger fault codes such as B2799
  • Car cranks but won't start

How to Reset a Toyota ECU

If your Toyota ECU is failing, you can try to reset it.

A straightforward method is to disconnect the negative and battery terminals. Then touch the two cables you just removed (not the battery posts) together for about two minutes. That will reset the engine control units in most cases. 

reset toyota ecu

If the above doesn't work, another method is to jump pins four and 13 in the OBD-II port. Use a paper clip between 4 and 13. Keep the paper clip connected for at least 30 minutes. Insert the key in the ignition, and you will notice P/S, airbag, ABS, and several other cluster lights. After 30 minutes, remove the paper clip, and the ECU will be reset.

According to many Toyota/Lexus/Scion owners, this procedure has worked on several models, including 2010 Toyota Tundra, 2003 Toyota Camry, 2005 Lexus LS430, 2003 Toyota Corolla, 2005 Toyota Sienna, Scion TC, 2011 Toyota Rav 4, 2007 Lexus ES350, 2009 Corolla, 2006 Lexus GX470, 2004 Camry, 2006 Toyota Prado, 2004 Highlander. This procedure may not work for newer models. 

This procedure can help, especially if your Toyota / Lexus starts and stalls immediately. 

What you will need

How to Replace Toyota Engine Control Unit (ECU)

  1. Open the hood. Pull the hood release under the dashboard. Go to the front, unlock the hood latch and pull the hood up until the hood struts are in hold position.Sliding the tab to unlock the hood latch.

     

  2. Disconnect the negative terminal by loosening the 10mm bolt and pulling the terminal out from the battery post.Disconnecting the negative terminal of the battery.

     

  3. Locate the Engine Control Unit (ECU) on the driver's side of the engine compartment, near the air filter housing.The Electronic Control Unit of the Toyota Camry.

     

  4. Remove the connectors by pressing the tabs, sliding the lock, and pulling the connector out.Unlocking the electrical connector of the ECUDisconnecting the electrical connector of the ECU.

     

    Disconnecting the electrical connector of the ECU.
  5. Remove the upper bolt on the right side of the ECU using a wrench.Removing the upper bolt on the right side of the ECU.

     

  6. Loosen the bolts on both sides of the ECU.Loosening the bolt holding the ECU.

     

    Loosening the bolt holding the ECU.
  7. Remove the ECU from the vehicle by pulling it up. Removing the ECU of the Toyota Camry.

     

    Removing the ECU of the Toyota Camry.
  8. Get the new Engine Control Unit and line it up to the metal plates holding the ECU.Installing the new ECU to the vehicle.

     

  9. Tighten and reinstall the bolts on the left side and right side of the ECU.Tightening the bolts holding the ECU.

     

    Tightening the bolt holding the ECU.
  10. Reconnect the electrical connectors of the ECU by pushing it in and sliding the lock on its position.Reconnecting the electrical connector of the ECU.Locking the connector on the ECU.

     

    Locking the connector on the ECU 2.
  11. Reconnect the negative terminal of the battery.Reinstalling the negative terminal of the battery.
  12. Jump pins 4 and 13 at the OBD-II port using a paper clip. Leave ignition on for 30 minutes with the paper clip connected to the OBD-II port. Turn off the ignition and remove the paper clip. 
  13. Start car. 

 

Remember that the new Toyota ECU will need to be programmed to work with your vehicle correctly. If the last step in the procedure does not work, you will need to visit a Toyota auto mechanic or access the techstream tool. 

Can you replace a Toyota ECU yourself? 

Yes, you can replace a Toyota ECU yourself, but it will need to be programmed once the ECU has been replaced. If the dealer sold you the ECU, they could program it for you for a small fee. 

If you installed a used ECU, the dealer will most likely not program it. You will have to find an independent repair shop to program it for you. 

How much does it cost to replace a Toyota ECU? 

The average price to replace a Toyota ECU at a dealership can range between $1500-$3500 depending on year and model. A cheaper alternative is to find an independent shop that will repair your existing Toyota ECU. You will have to remove the ECU from the car and ship it to the shop. The repair can range between $300 and $500.

How can I program a Toyota ECU? 

George from Melnik Automotive shows you how to program a Toyota/Lexus ECU via the OBD-II port in the following video. 

The procedure to program a Toyota ECU is straightforward. It requires 30 minutes and a paper clip. 

program  toyota ecu
  1. Replace ECM with factory new or used. 
  2. Jump pins 4 and 13 on the OBD-II port under the dashboard using a paper clip. 
  3. Leave the ignition on for 30 minutes. P/S, ABS, traction, and other warning lights will stay on or flash. 
  4. After 30 min turn off the ignition. , remove the paper clip from the OBD-II port.
  5. Star the car

Can you drive a Toyota with a bad ECU? 

It isn't recommended to drive a Toyota with a faulty ECU. If the ECU will even allow you to start the engine, the problem is that it can malfunction while during, which can be dangerous and can lead to an accident. 

 

Everything You Need to Know about Toyota ECU Common symptoms of a bad Engine Control Unit (ECU) on a Toyota. How to reset a Toyota ECU. Step-by-step procedure on how to replace the Engine Control Unit (ECU) on a Toyota.